DIFFERENTIAL SCREENING OF TRYPANOSOMA CRUZI ANTIGENS

恰加斯病是一种由原动质体原生动物克氏锥虫引起的潜在致命性疾病。这种有机体在大多数拉丁美洲国家流行，有1 600万至1 800万人受到感染，它不仅对这些国家的血液供应构成威胁，而且对美国的血液供应也构成威胁。大多数慢性感染者是无症状的，终生处于所谓的疾病不确定阶段。然而，在10- 30%的感染者中，出现慢性恰加斯病的典型心脏和胃肠道症状。在此应用中提出的克氏T.抗原的研究有三个长期目标：(1)了解发病机制中涉及的免疫过程，(2)改进血清学诊断方法，(3)确定疫苗开发的潜在候选物。我们建议评估重组克氏T.抗原在两组慢性感染恰加斯患者（无症状者和恰加斯心肌病患者）中引起的体液和细胞免疫反应。自1990年以来，这些患者一直在圣保罗大学医院的移植免疫学实验室进行研究。通过免疫筛选这些血清的无梭菌cDNA文库，我们计划鉴定两组患者免疫应答识别的抗原。每个重组抗原将测试其与来自每个患者的血清和外周血单核细胞（pmbc）的反应性。我们假设将发现两类抗原：(a)刺激控制寄生虫感染的B细胞和/或T细胞反应的潜在保护性抗原，这些反应预计在无症状患者中更为普遍；(B)含有寄生虫和哺乳动物细胞共享的表位的交叉反应性抗原，这些抗原更有可能使用可能存在自身免疫反应的心脏病患者的血清来识别。我们的研究将验证抗体和/或细胞对一些纯化寄生虫抗原的反应是否与克氏锥虫感染的病程有关。

Chagas disease is a potentially fatal disease caused by the kinetoplastid protzoan Trypanosoma cruzi. This organism is endemic in most Latin American countries where 16-18 million people are infected, and it constitutes a threat to the blood supply not only in those countries but also in the United States. The majority of chronically infected person are asymptomatic and remain for life in the so-called indeterminate phase of the disease. In 10-30 percent of infected individuals, however, cardiac and gastrointestinal manifestations typical of chronic Chagas disease occur. The study of T. cruzi antigens proposed in this application has three long-term objectives: (1.) to understand the immune processes involved in pathogenesis, (2.) to improve serological methods for diagnosis and (3.) to identify potential candidates for vaccine development. We propose to evaluate recombinant T. cruzi antigens for the humoral and cellular immune responses they elicit in two groups of chronically infected chagasic patients: asymptomatic persons and patients with chagasic cardiomyopathy. These patients have been studied in the Transplantation Immunology Laboratory of the Sao Paulo University Hospital since 1990. By immunoscreening an amastigote cDNA library with these sera, we plan to identify antigens that are recognized by the immune responses of the two groups of patients. Each recombinant antigen will be tested for its reactivity with sera and peripheral blood monocytes (PMBCs) derived from each patient. We hypothesize that two classes of antigens will be found: (a) potentially protective antigens that stimulate B- and/or T cell responses controlling the parasitic infection, responses expected to be more prevalent in asymptomatic patients, and (b) cross-reactive antigens containing epitopes shared by the parasite and mammalian cells that will be more likely identified using sera from cardiac patients with possible autoimmune reactions. Our studies will verify whether there is a correlation between the antibody and/or cellular response to a number of purified parasite antigens and the course of the T. cruzi infection.